He is pretty active on his community Discord, providing weekly updates. Right now, he has spent the last year working on additional content for Lunar Crisis.
He sounds like he's mostly decided on his next game project, but hasn't really shared anything specific about it yet and hasn't started working on it as far as we know. He's casually mentioned a lot of different possibilities: an action game with a zombie setting, a strategy/tactical game with an isometric "Diablo" style camera, a fantasy game, some kind of RPG, and another game taking place in the same world as Xenotake/Lunar Crisis.
Last I remember hearing, the strategy game idea was "runner up for the next game after Lunar Crisis" — which means that he has a clear favorite, but hasn't said which one it is. Though you can safely cross the Xenotake/Lunar Crisis game off the list for now because he sounds like he really wants to do something new first.